PIC QUESTION OF THE WEEK: 12/07/09
Q: Please discuss the recent FDA Health Advisory on the interaction between clopidogrel and omeprazole?
A: A previous issue of this publication (PIC Question of the Week 2/09/09) reviewed the possible reduction in
the effects of clopidogrel when used in combination with proton pump inhibitors (PPIs). A number of studies
have subsequently been published regarding the concomitant use of clopidogrel and omeprazole (a CYP2C19
inhibitor). The Food and Drug Administration (FDA) has recently issued a Public Health Advisory with
updated safety information on the effects of combining clopidogrel and omeprazole. The agency cites one
study in which patients receiving combination therapy had a 45% reduction in the level of clopidogrel active
metabolites and a 47% decrease in anti-platelet effects when compared to those only receiving clopidogrel.
These effects were observed regardless of whether the drugs were administered simultaneously or separated by
twelve hours. As a result of this new information, the clopidogrel label has been updated to include details of
the new studies and warnings of its possible interaction with omeprazole and other CYP2C19 inhibitors.
Additional CYP2C19 inhibitors include esomeprazole, cimetidine, fluconazole, ketoconazole, etravirine,
felbamate, fluoxetine, fluvoxamine, and ticlopidine. Currently, there is no evidence that H2-antagonists
(excluding cimetidine) or antacids affect clopidogrelâ&#x20AC;&#x2122;s anti-platelet activity nor is there sufficient evidence
associating other PPIs with this interaction. While the FDA does not have sufficient information to make more
specific recommendations, healthcare professionals are advised to consider these possible interactions in all
patients treated with clopidogrel. This topic will continue to be evaluated and further information is scheduled
to be presented at the next meeting of the FDAâ&#x20AC;&#x2122;s Drug Safety Oversight Board. The American College of
Cardiology (ACC) and the American Heart Association (AHA) responded to this FDA advisory by replying that
it was not based on any newly published, peer-reviewed clinical trials showing changes in cardiovascular
outcomes. Regardless of this opinion, the FDA recommends that patients receiving clopidogrel not be
administered any of the prescription or over-the-counter (OTC) formulations of omeprazole.
References:
American Heart Association. American College of Cardiology/American Heart Association Comment on the FDA Public
Health Advisory regarding a drug interaction between clopidogrel and omeprazole.
http://americanheart.mediaroom.com/index.php?s=43&item=896 Accessed 19 November 2009.
Food and Drug Administration. Public Health Advisory: Updated safety information about a drug interaction between
clopidogrel bisulfate (marketed as Plavix) and omeprazole (marketed as Prilosec and Prilosec OTC).
http://www.fda.gov/Drugs/DrugSafety/PublicHealthAdvisories/ucm190825.htm Accessed 19 November 2009.
Food and Drug Administration. Information for Healthcare Professional: Update to the labeling of clopidogrel bisulfate
(marketed as Plavix) to alert healthcare professionals about a drug interaction with omeprazole (marketed as Prilosec and
Prilosec OTC).
http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/DrugSafetyInformationfor
HeathcareProfessionals/ucm190787.htm Accessed 19 November 2009.
Photo by: ZedZap(Nick): used under Creative Commons License; http://www.flickr.com/photos/zedzap/3311789513/
(Accessed 18 November 2009)

Samantha K. Adams and Brian R. Lohr, Pharm.D. Candidates
The PIC Question of the Week is a publication of the Pharmaceutical Information Center, Mylan School of
Pharmacy, Duquesne University, Pittsburgh, PA 15282 (412.396.4600).